Item

Test Condition

Unit Symbol

95%Alumina 

ceramics

99%Alumina 

ceramics

99.7%Alumina 

ceramics

The main chemical

ingredient

Al2O3

Al2O3

Al2O3

Bulk Density

g/cm3

3.6

3.89

3.96

Maximum Use 

Temperature

1450℃

1600℃

1650℃

Water absorption

%

0

0

0

ROHS Hardness

≥85

≥89

≥89

Flexural strength

20° C

MPa (psi x 103)

358 (52)

550

550

Compressive Strength

20° C

MPa (psi x 103)

2068 (300)

2600(377)

2600(377)

Fracture Toughness

K(I c)

Mpa m1/2

4-5

5.6

6

Coefficient of 

thermal expansion

25-1000° C

1X 10-6/°C

7.6

7.9

8.2

Coefficient of 

thermal conductivity

20° C

W/m °K

16

30.0

30.4

Thermal Shock 

Resistance

Tc

°C

250

200

200

Dielectricity constant

1MHz.25℃

9

9.7

9.7

Dielectric strength

ac-kV/mm (ac V/mil)

8.3 (210)